In the past liquid photopolymer printing plate blanks were formed by dispensing a pool of photopolymer in front of a doctor blade which spread and shaped the polymer as illustrated, for example in U.S. Pat. No. 3,597,080 which depicts in general a current commercial embodiment.
While present photopolymer printing plates are rectangular in shape it has been very difficult in the past to maintain complete reproducibility in configuration in forming the liquid photopolymer printing plate blanks with straight sides. The tendency in the past has been for the sides to draw in or bulge out or extend out a greater distance at the top or bottom of the laydown particularly at the bottom of the laydown on one edge rather than being straight across. In order to assure a sufficiently large area that is of a uniform thickness and within the length and width requirements of the sheet of the viscous liquid plate blank it is necessary to add additional margin, which wastes polymer, even with the recycling of most of the excess. Furthermore it has been necessary to constantly readjust and fine tune the dispensing and shaping apparatus during a day's run to keep reasonable uniformity of size within the required thickness specifications.
It is therefore an object of the present invention to prevent the waste of polymer.
It is a further object of the present invention to increase the quality of the printing plate blank produced and thereby increase the quality of the printing plate produced.
It is a further object of the present invention to save manpower required in adjusting and operating the apparatus.
It is yet a further object of the invention to increase the speed of printing plate output, increasing the number of blanks that can be produced in an hour.
It is a further object of the present invention to produce an apparatus that is less expensive and simpler in construction, maintenance and operation than those previously employed.